Burner ignition and control system



Sept. 7, 1965 M. w. PATRICK BURNER IGNITION AND CONTROL SYSTEM FiledFeb. 15, 1963 INVENTOR Malcolm M. Patrick ATTORNEYS vice problems.

United States Patent 3,204,685 BURNER IGNITION AND CONTROL SYSTEMMalcolm W. Patrick, Redford, Ohio, assignor to Hupp Corporation,'Cleveland, Ohio, a corporation of Virginia Filed Feb. 15, 1963, Ser.No. 258,684 4 Claims. (Cl. 158-125) This invention relates to controland ignition systems for fluid fuel burners and more particularly tosuch systerns which open and close a fuel valve and time the operationof a spark ignitor.

While the present invention has particular utility in connection withthe control of gas burners installed in domestic heating systems, theinvention may also be used to control other types of fluid fuel burners,for example,

oil burners, and may be used for other types of heating plants such asthose installed in commercial and industrial establishments.

In general, of the ignition and control circuits available in the past,those which have provided for safe operation have been expensive,complicated and diflicult to service. Simplicity and low cost have beenachieved only at the expense of the elimination of one or more necessarysafety features.

Certain prior systems, such as those which utilize a continuouslyburning gas pilot which burns throughout the heating season requireexpensive safety controls and in most areas involve a high cost ofoperation. Other prior systems, in which a gas is ignited by an electricignitor when heat is required, waste less gas than the continuous pilotbut require more complicated controls to time the spark, control the gasto the pilot, and to guard against unsafe conditions. Possibilities forignition failure in such a system are substantial.

It has also been proposed to ignite the main gas flame directly by a hotwire resistance coil. This system, however, has been found to beunreliable since low voltage causes ignition failure while high voltageburns out the ignitors in a short time. If the system includes apparatusto discontinue the flow of gas to the ignitor after ignition has occuredthe cost of the system becomes relatively high.

Prior systems in which the main burner is ignited directly by acontinuous spark require a heavy duty spark transformer, which isrelatively expensive, and means to prevent radio interference as well asthe usual relatively been costly, complicated and difficult to service.In such a system it is necessary to insure a spark at the time the gasis turned on, that successful ignition is effected, that the gas flowstops in the event the burner is not ignited or if the gas flow ismomentarily discontinued, that if the burner shuts off the ignitor doesnot become operative again until there has been time for the accumulatedgas to be cleared from the furnace, and finally in case of failure ofany component of the control system a dangerous condition will not beproduced.

Many prior control systems have incorporated electronic devices such asphotoelectric cells, amplifiers, rectifiers, and other devicesincorporating vacuum tubes and/ or transistors. All of these systemshave been expensive and complicated and have involved serious ser- Withthese considerations in mind it is a principal purpose and object of thepresent invention to provide improved control and ignition systemsparticularly adapted for use with gas fired home heating plants whichare simple, compact and inexpensive and yet which provide completelysafe operation under all ponents, as well as the spark 16 and thetransformer 18.

3,264,685 Patented Sept. 7, 1965 operating conditions even when acomponent of the system fails to operate.

It is also an object of the invention to provide improved ignition andcontrol systems for fuel burners which control the energization of anelectrically operated gas valve and a high voltage circuit across thespark gap, the systern functioning so that upon closing a switch or athermo stat, gas will flow to the main burner to be ignited by a sparkwhich is discontinued after ignition is effected, the system alsoincorporating means to discontinue the flow of gas and the spark if theburner fails to ignite within a predetermined time as well as meansto'discontinue compact and provides for completely safe operation.

It is an additional object of the present invention to provide improvedcontrol and ignition systems for gas .burners of the type referred toabove, which, in case of failure of any of its components, will maintainthe main fuel valve in closed position.

Additional objects and advantages of the present invention will becomeapparent as the description proceeds in connection with the accompanyingdrawing which is a schematic diagram showing the components of thesystem in a typical installation.

In this figure the ignition and control system of the present inventionis shown in connection with a conventional gas burner 10 of the typewhich may be em ployed in a domestic heating plant. The burner issupplied with gas from a main gas conduit 12, the flow of gas beingcontrolled by a solenoid valve 14 of conven tional construction, whichis spring biased to the closed position and is opened by actuation ofits associated solenoid coil. The burner 10 is ignited by a spark 16 inseries with the secondary coil of a transformer 18.

The control circuit of the present invention which is connected to powerlines 19 and 20 as described in detail below, includes a master switch22, a room thermostat 24, a warp switch assembly 26, a relay 28 havingnormally open contacts 30, a relay 32 having normally open contacts with34 and normally closed contacts 36 and a temperature sensitive switchassembly often termed a flame switch indicated generally at 38. All ofthese comare relatively low cost items which are available through anumber of commercial sources.

The warp switch assembly 26 includes a bi-metallic blade 42 whichmaintains the contact 40 normally closed and opens the contact 40 whenthe blade 4-2 is heated by a resistor unit 44.

The flame switch assembly 38 includes contacts 46 and 48 which areadapted to be opened and closed by a swinging blade 50 biased by aspring 52 to maintain a circuit through the contact 46 and is moved tothe dotted line position to close contact 48 by a plunger 54 carried bya diaphragm 56 connected by a capillary tube 58 to a bulb 60 positionedclose to the burner ll). As is well known in the art the bulb 60 may befilled with a fluid such as mercury which expands when heated todisplace the diaphragm 56 and move the switch blade 50 from its fullline or cold position to its dotted line or hot posithe valve from itsclosed position.

tact 48 when the burner is in operation. The many electrical leadsconnecting the various components will not be described individuallysince they are clearly disclosed in the drawing and that ollowingdescription of the operation of the system. I

The control system is shown in its completely deenergized position withthe burner 10 and the spark 16 out of operation, the main circuit beingopen at the master switch 22. The system may be readied for operation byclosing master switch 22 and setting the thermostat 24 as desired. Untilthe thermostat closes the system will remain in the condition shown inthe drawing.

When the thermostat 24 closes, a circuit is completed from the mainpower line 19 through the switch 22 to the thermostat 24 and the warpswitch contacts 40, a resistor 62 connected in parallel with the relaycontact 30, and

' through valve 14 to main power line 20. Because of the size of theresistor 62 the current flow is not sufiicient to open the valve 14.

Simultaneously, a circuit is made through the resistance heater 44, therelay 28, the cold contacts 46 of the flame switch 33 to the power line20. Contacts 30 are then closed shorting out the resistance 62 to openvalve 14 and completing a circuit through primary 64 to energizeenergization of relay 28 opens contacts 30 so that thecircuit throughthe solenoid valve 14 is made only through the resistance 62. Thecurrent flow in this circuit is sufficient to hold valve 14 open but notsuflicient to open When the hot contact 48 closes, a circuit iscompleted to the relay 32 which opens contact 36 and closes contact 34.The opening of contact 36 deenergizes the spark 16. The closing ofcontact 34 completes a shunt circuit around the hot contact 48.

The system will continue in this manner with the burner in operation andthe spark 16 deenergized until the thermostat 24 is opened by anincrease in temperature in the space served by the burner 10. When thethermostat opens, the circuit to the valve 14 is opened and In the eventignition of the main burner 10 is not effected, the warp switch heater44 will continue in operation since the cold contact 46 of the flameswitch 38 remains closed. After a predetermined time, which can be setas desired, the resistance heater 44 will cause switch contact 40 toopen thus immediately deenergizing the spark 16 and closing the valve14.

Similarly, in the event the main burner]10 becomes extinguished afterignition, the flame switch 38 will move to close contact 46 and opencontact 48. The closing of the contact 46 will energize the warp switchheater 44 to open the circuit through the valve 14. In either event,that is where the burner initially fails to ignite or there is a failureof combustion after ignition, the circuit cannot be restored to itsoriginal condition for reignition without first opening the main switch22 to deenergize the heater 44 and permit the switch blade 42 to cool.Since the cooling of the switch blade 42 requires several minutes, ampletime is permitted to permit the dissipation of any gas accumulated inthe furnace.

It is a feature of particular importance of the present invention thatfailure of one or more of the electrical When contact 46 is opened thecircuit through 30V soon as ignition were effected and opened.

components of the system does not produce an unsafe condition, i.e.,that the entire system in all respects fail safe.

For example, in case of any type of failure of the flame switch assembly38, the contact 46 will remain closed keeping the warp switch heater 44in the circuit to open the contact 40 to thereby close the main gasvalve 14 and deenergize the spark 16. In the event of failure of theresistance element 44 or the relay 28, contacts 30 remain open,preventing opening of the valve 14. In the event that the resistor 62burned out, valve 14 would close as contact 36 were system in accordancewith the objects set forth above.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics therefore. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come Within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:

1. An ignition and control system for a fluid fuel burner comprising anormally closed solenoid operated valve for controlling the supply offuel to said burner; spark ignition means for said burner; power circuitmeans for said valve and said ignition means; a normally closed warpswitch in said circuit; normally open relay contacts 'and a resistorconnected in parallel in said circuit, said relay contacts and saidresistor each being in series with said warp switch and said valve, saidrelay contacts being in series with said spark ignition means, theresistance of said resistor being such that the current flow throughsaid resistor is suflicient to hold said valve open but insufiicient toopen said valve; main switch means for connecting said circuit to apower source; a combustion sensor including a pair of normally closedcontacts and a pair of normally open contacts, said normally closedcontacts. being open and said normally open contacts being closed whensaid combustion sensor is heated by combustion of said burner; meansincluding said normally closed contacts of said combustion sensoroperative when f'said main switch means is closed and said valve isclosed to close said relay contact to open said valve and to energizesaid spark ignition; said combustion sensor opening said normally closedcontacts and thereby opening said relay contacts upon initiation ofcombustion at said burner whereby the circuit to said solenoid valve ismaintained through said resistor and said spark means is 'deenergized,and a heater in series with said normally closed contacts and operableto open said warp switch a predetermined time after said main switchmeans is closed. 2. -An ignition and control system for a fluid fuelburner, said system comprising circuit means between first and secondpower lines of opposite polarity and incorporating switch meanscontrolling flow of current in said relay incorporating a normallyclosed pair of contacts and a normally open pair of contacts, saidnormally closed contacts opening and said normally open contacts closingwhen said second relay is energized, a normally closed electricallyenergized fuel valve which permits fuel to flow to said burner whenenergized, an electric ignitor adapted to ignite fuel at said burnerwhen energized, a combustion sensor incorporating a normally closed pairof contacts and a normally open pair of contacts, said normally closedcontacts opening and said normally open contacts closing when saidcombustion sensor is heated by combustion at said burner, a resistor inseries with said fuel valve and having a resistance allowing sufficientpower input to said valve when energized to maintain said valve in opencondition but less than required to open it when closed, said circuitmeans between said power lines including circuits (1) through saidresistance heater, said first relay and the normally closed contacts ofsaid combustion sensor,

(2) through the normally closed contacts of said warp switch, saidresistor and said fuel valve,

(3) through the normally closed contacts of said warp switch, thenormally open contacts of said first relay when closed, and saidignitor,

(4) through the normally closed contacts of said warp switch, thenormally open contacts of said first relay when closed, the normallyclosed contacts of said second relay and through said valve,

(5) through said second relay and the normally open contacts of thecombustion sensor when closed,

(6) through said second relay and its normally open contacts whenclosed; whereby when said switch means is closed, circuits (1) and (2)are completed, causing the normally open contacts of said first relay toclose, completing circuits (3) and (4) thus energizing said valve andsaid ignitor; when combustion is established the normally open contactsof the combustion sensor will close and the normally closed contactswill open, breaking circuit (1) which opens the contacts of said firstrelay breaking circuits (3) and (4), and completing circuit (5) whichenergizes the second relay to complete circuit (6), thus maintaining thevalve open and deenergizing the ignitor; while if combustion fails,continued energization of circuit (1) will cause the normally closedcontacts of the warp switch to open, breaking circuits (2), (3) and (4),which will deenergize said valve and ignitor.

3. An ignition and control system according to claim 2, wherein saidignitor incorporates a transformer having its primary winding in saidthird circuit and its secondary winding in series with a spark plugwhich has its spark gap adjacent to said burner.

4. An ignition and control system according to claim 2, wherein saidswitch means incorporates a manual switch and a thermostat connected inseries.

References Cited by the Examiner UNITED STATES PATENTS 2,167,227 7/39Wilson 158-28 2,720,254 10/55 Ward 15828 2,730,169 1/56 Deubel 1581252,800,176 7/57 Morrison 158-125 2,887,152 5/59 Wilder 158-28 3,059,69310/62 Hotchkiss 158-125 JAMES W. WESTHAVER, Primary Examiner.

FREDERICK L. MATTESON, JR., Examiner.

1. AN IGNITION AND CONTROL SYSTEM FOR A FLUID FUEL BURNER COMPRISING ANORMALLY CLOSED SOLENOID OPERATED VALVE FOR CONTROLLING THE SUPPLY OFFUEL TO SAID BURNER SPARK IGNITION MEANS FOR SAID BURNER; POWER CIRCUITMEANS FOR SAID VALVE AND SAID IGNITION MEANS; A NORMALLY CLOSED WARPSWITCH IN SAID CIRCUIT; NORMALLY OPEN RELAY CONTACTS AND A RESISTORCONNECTED IN PARALLEL IN SAID CIRCUIT, SAID RELAY CONTACTS AND SAIDRESISTOR EACH BEING IN SERIES WITH SAID WARP SWITCH AND SAID VALVE, SAIDRELAY CONTACTS BEING IN SERIES WITH SAID SPARK IGNITION MEANS, THERESISTANCE OF SAID RESISTOR BEING SUCH THAT THE CURRENT FLOW THROUGHSAID RESISTOR IS SUFFICIENT TO HOLD SAID VALVE OPEN BUT INSUFFICIENT TOOPEN SAID VALVE; MEAIN SWITCH MEANS FOR CONNECTING SAID CIRCUIT TO APOWER SOURCE; A COMBUSTION SENSOR INCLUDING A PAIR OF NORMALLY CLOSEDCONTACTS AND A PAIR OF NORMALLY OPEN CONTACTS,SAID NORMALLY CLOSEDCONTACTS BEING OPEN AND SAID NORMALLY OPEN CONTACTS BEING CLOSED WHENSAID COMBUSTION SENSOR IS HEATED BY COMBUSTION OF SAID BURNER; MEANSINCLUDING SAID NORMALLY CLOSED CONTACTS OF SAID COMBUSTION SENSOROPERATIVE WHEN SAID MAIN SWITCH MEANS IS CLOSED AND SAID VALVE IS CLOSEDTO CLOSE SAID RELAY CONTACT TO OPEN SAID VALVE AND TO ENERGIZE SAIDSPARK IGNITION; SAID COMBUSTION SENSOR OPENING SAID NORMALLY CLOSEDCONTACTS AND THEREBY OPENING SAID RELAY CONTACTS UPON INITIATION OFCOMBUSTION AT SAID BURNER WHEREBY THE CIRCUIT TO SAID SOLENOID VALVE ISMAINTAINED THROUGH SAID RESISTOR AND SAID SPARK MEANS IS DEENERGIZED,AND A HEATER IN SERIES WITH SAID NORMALLY CLOSED CONTACTS AND OPERABLETO OPEN SAID WARP SWITCH A PREDETERMINED TIME AFTER SAID MAIN SWITCHMEANS IS CLOSED.